Cause-and-effect diagrams are typically used for problem reformulation and search of a root cause of an undesirable event. One of the first cause-and-effect diagrams was developed by Kauro Ishikawa of Tokyo University in 1943 and thus are often called Ishikawa Diagrams. They are also known as fishbone diagrams because of the appearance of the diagrams (in a plotted form). See, e.g., FIG. 7. Such a fishbone diagram may reflect different categories of causes. Each possible event is conventionally placed on an appropriate category line. The cause-and-effect diagram systematizes reasons by categories but does not provide a possibility to show causal links between given causes. Thus, each cause may affect one initial undesirable event, but conventionally there may be no provision to determine how multiple causes may be linked between one another.
Another conventional diagram for root cause analysis (RCA) is a cause-and-effect tree. The cause-and-effect tree may be organized in tree chains of cause and effect. Conventional tools are available and may be used to provide a logic tree structure such as, e.g., but not limited to, PROACT® Root Cause Analysis (RCA) v3.0 available from Reliability Center, Inc., of Hopewell, Va., USA. See, e.g., FIG. 8. In each tree chain, each previous event may be a cause for a next one. So, if one cause is prevented, then all next causes in the chain may be prevented as well.